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From twigs and grasses to sheep’s wool and horsehair, birds weave their world into their nests. The homes they leave behind thus provide clues about their lives and their environment, much as archaeological sites supply glimpses of human history.

The architectural diversity of nests has been used to untangle the complex genealogy of South American songbirds; remnants of prey found in bald eagle nests have revealed the birds’ food habits; and carbon dating of feathers and droppings in ancient falcon nests has yielded evidence for the timing of ice-sheet retreats in Greenland. Ongoing research, including a paper published in the journal Science earlier this year, shows that birds use nest decor to compete for mates and communicate with one another more often than previously recognized.